Testing device



H. O. HEM

TESTING DEVICE June 11, 1940.

, 1939 4 Sheets-Sheet 1 Filed Jan. 11

Ha/Vor 0. Hem

ATTORNEYS H. o. HEM

TESTING DEVICE June 11, 1940.

Filed Jan. 11, 1939 4 Sheets-Sheet 2 l /d/laf 0. H607 INVENTOR ZWWMZkWZZL ATTORNEYS L 1 l6 /0 R1 g Ha/ror, 0. Hem

June 11, 1940. H. o. HEM' 2,203,782

TESTING DEVICE Filed Jan. 11, 1939 4 Sheets-Sheet 4 57 I ZZWQ/ZZWWMS Patented June 11, 1940 PATENT OFFICE T T rss'rme DEVICE e e T Halvor 0. Hem, Toledo, Ohio, assignor to Toledo;

T Scale Manufacturing Company, Toledo, Ohio,

acorporation o f New Jersey h e e Application January 11, 1939, Serial No. 250,398

12 china; (01. 73-53 T This invention relates generally to testing devices, and more particularly todevices for statically balancing and reproducing blades for propellers such as are used on aircraft or other de- .3 vicesemploying air screws. T T It has heretoforebeen customary to reproduce propeller blades in. conformity with a master. Such master blades, however, must be permanently retained for reference purposes and furthermore a master blade must be supplied to each source of supply of thatblade. Thewastefulness of this method in both time and money is obvious. The primary object of this invention is a device for quantitatively determining a plurality of static moments of a propeller blade. T T

proved propeller blade balancing device in whichthe longitudinal static moment and the transverse static moment about its longitudinal axis may be determined in definite. units, such as inch-pounds.

These, and other objects and advantages willbe apparent from the following description in which reference is had to the accompanying drawings,T

illustrating a preferred embodiment of the in- T refer to similar parts views. T

Referring to the drawings: T Fig. I is a front elevational view of the device. Fig; II is a plan view thereof. T T T Fig. III is an enlarged, fragmentary front elethroughout the several T Tvational view, parts brokenaway and others sec T tioned along theline III-III;of Fig. II. T

Fig. IV is an enlarged, transverse sectional view substantially along the line IVIV of Fig; II. M

Fig. V is an enlarged, transverse sectional view sectional substantially along the line V--V of Fig. III. T FignVI is an enlarged, fragmentary sectional view of one of the locking means, itbeingsectioned substantially along the line VIVI of Fig.

II. T T e T T T Fig, VII is an enlarged fragmentary transverse Another object is the provision of an improved T sectional view substantially along the line VII- VII of Fig. III. T T

Fig. VIII is an enlarged, sectional view substantially along the line VIIL-VIII of Fig. III, and showing in detail Ta .micrometerpoise actuating T means. T T

Fig. IX is an enlarged,.fragmentary plan view of the micrometer poise as seen substantially from along the line IX--IX of Fig. III; and,

Fig. X is a transverse sectional view substantially along the line X-X of Fig. III.

Referring to the drawings in detail:

The device comprises a base l B uponwhich are mounted, adjacent one of itsends,'a pair of fulcrum stands I! having V bearings l2 in theirupper ends. These V bearings l2 form seats for fulcrum pivots I3 which span bifurcations in 1ongitudinal arms 14 of a beam [5. The arms Ml are connected by transverse members It and I1 and the member i6 is provided with an integral lipwardly extending fulcrum stand; I8. A fulcrum stand I9 is also an integral part of the trans verse member 1". A V bearing 2|), which is alignablyseated in the TuDDer end of the fulcrum standlB, supports whose. opposite end is provided with an upwardly directed knife edge 25 in a pivot 26 which spans the spaces formed by three transversely extending webs 27, and engages the downwardly di T rected V of a bearing 28 adjustably seated in the fulcrum stand l9. Another knife edge 29 of the pivotT26, collinear with the knife edge 25, but facingin the opposite direction, engages a bearing 3i! T rockably mounted in a bracket 3i fixed to the upper end of a rod 32 which is slidably seated in avertical bore in an extension 33 of thetransverse member I! of the beam 15. A helical spring 34, circumjacently mounted on the rod 32 and seated on the extension 33', urges the pivot 26 upwardly and its knife edge 25 into close engage- Tment with the inverted V of the bearing 28. Cona concentric circular bore 39 in which is seated T closely engage the contour ofv this shank. An I inwardly extending flange 44 on the outer. end

of the receiver II is adapted to engage with a shoulder on the shank and cooperate with a clamp member 45 threaded through the boss 46 to securely clamp the blade 43 in horizontal position.

To relieve the strain on the receiver ll when a propeller is clamped therein by supporting its free end, extensions 46 are bolted to arms 38' extending transversely and forwardly on each side of the flange 39 of the lever 24 and a cross arm 4'I is adjustably mounted on these extensions 45; This cross arm is provided with stops 48 adapted to beadjusted so that they may enxgage the lower surface of the blade' 43.

' to and after such blade has been attached for For a purpose which will later become clear, the transverse member it of the beam I5; on the longitudinal axis of the lever 24, isiprovided with two upwardly'extending arms 49 having bores Which are collinear with the edge of the pivot 2| in the lever 24. I Threaded in these bores are thrusts 59 and 5! having inwardly directed turned-down portions 'which enter bores in parallelly disposed arms 52 of a handle 53 in which they are locked by means of pins 54.

:Since one of these thrusts, for example 50, is

provided with a left hand thread and theother thrust ill with a right hand thread, rotation of the handle 53 in one direction causes the thrusts 50 and M to slightly approach each other, bending the relatively flexible arms 52 of the handle and to engage the opposite ends of the pivot 2 I, in the lever 24, which is positioned between them. Rotation of the handle 53 in the opposite direction however, causes these thrusts 5| and 52 to recede and free the pivot 2!.

Means are provided for indicating the condi- 'tion of balance of the beam I5 and the lever 24 before a propeller blade has been clamped theredetermining its static moments. For cooperation when determining the longitudinal static moment of a blade these means comprise a short integral arm 55, extending laterally from the beam I5, having two upwardly extending ears 56 between which a power pivot M is seated. This power pivot 57! engages a stirrup, 58 suspended from a connecting rod 59 whose upper end, by means of a stirrup 60, engages a load pivot SI. fixed in an arm of a pendulum I52, fulcrumed by means of a pivot 63 on V bearings in a bracket 64 secured to a wallof an indicator housing 65 surmounting an extension 66 which is bolted in proper position to the base I'll. An upwardly directed indicator 61. secured to the pendulum 62 by means of screws 68. cooperates with an indicium 69 on a chartIlJ fixed in the upper portion of a housing 65. For indicating I the condition of balance of the lever 24 about its rup I3 is suspended from the lower end of a connecting rod I4, Whose upper end is provided or the poise. I turning with the screw by the action of apin with a stirrup I5 engaging a pivot "I6 in an arm of a pendulum I'I fulcrumed by means-of a pivot "I8 upon a bracket I9 in the interior ofa housing which surmounts an extension 8| fixed to a shalf 82 of the beam I5 (Figures IX and X).

This pendulum II is also provided with an up-' wardly extending indicator 83 to cooperate with an indicium 84 on a chart 85 stationed in th housing 80.v

Since, however, it is an object "to quantitative- 1y determine the static moments of the propeller I blade being tested there is provided a cylindrical poise 85, threaded upon a micrometer screw 86 locked between two armsB'I extending inwardly from one of the longitudinal arms I4 of the beam I5. Also secured to this arm I4, in such a manner that. it partially overlaps the Y poise 85, is'a plate 88 (Fig. X) provided with a series; ofgraduations 88'. These graduations cooperate with a datum line 85 extending aroundthe periphery of the poise 85. The poise 85 is so'calibrated with respect to the threads of thescrev'v 86 and the graduations on the plate that one complete turn of the poise represents one inch-pound and advances the datum line from one graduation to another. the'poise 35 is provided with a series of gradu- -ations 85 eachof which represents a fraction The body of of aninch-pound.

To establish a transverse static moment of a propeller blade quantitativelyin inch-pounds, or

other definite units, a micrometer poise 89 is provided. This micrometer poise 89 (Figures VIII and IX) comprises a top member 9i! and a bottom member 9| seatedrespectively in machined ways on the top and bottom of the longitudinal arms 23 of the lever 24. These members 99 and Stare connected by vertical plates 92 and 93 and are assembled into a unit by means of screws 94 in such manner'that the assembled unit may slide K freely in a direction transverse .to the pivotal axis of the lever 24'. The weight of this frame-like poise is-carefully adjusted by removing metal by drilling holes in the member 9I. The plate 96 is provided with a series 950i indicia and a line 96 threaded on an end projecting beyond one'of the arms 23 of the lever 24". A shoulder 99 serves as a locating stop. The micrometer screw 91, so that it may be readily turned, has pinned to its other projecting end a hand knob 'IGII and a graduated dial IUI- which is integral with the knob. A series I02 of graduations marked on this dial cooperates'with an index I'Il3,engraved on a polished spot on the lever 24 immediately in back of the dial IIJI.

. To eliminate any possibility, of lost motion between the screw 91 and the poise 89 a helical spring I94 is circumjacently mounted upon the screw 9,! between the vertically extending plate 92 and a not I which is threaded upon the screw 9'! closely adjacent the vertical plate 93 This nut I95 is prevented from I I16 studded into the nut and projecting freely Ill) The screw9l is held 1 against endwise movement by nuts 93 which are into a hole" drilled :inthe plate'93. The bias of \75 tion so that thesame sides of the threadson the screw and in the plate 92 are always in engagement regardless in what direction the screw is turned. A clamp I! is adapted to lock the poise 89 in adjustedpositiony I During onephase in the determination of the static moments of a propeller blade it is necessary that the lever 24 be locked against movemenu relative to the beam I5.

This is also a necessary operation when a propeller blade is is integral therewith, the latch turned so as to lock the extending arm W3 oi termined. To accomplish this. a post studded into the base being. mounted in or is being removed from the receiver M. For this purpose, the lever 24 is equipped with a horizontal arm Hi8 which extends .(Fig. VII) into a trig lock Iilillarising from the beam I5. This trig lock comprisesspaced posts H0 whose upper ends support the ends of a short shaft III upon which a latch H2 is retatably seated. By turning a handle H3, which H2 may be the lever 26 against a bar II I extending between the posts Ilil and thus prevent the lever 26 from rocking on its pivots. The beam I must also be locked when a propelleris being inserted or removed, while Work is performedthereon and when thetransverse static moment is being de- H5 is It so that it projects through an aperture H5 in the transverse member I? of the beam I5. To the upper end of this post H5 is pivotally secured a bifurcatedcamlike loc'kingmember II'I, fulcrumed on a pin H3 which passes through the spaced arms of this member II! and througha bore in the post I I5. When the member H1 is turned by means of an integral handle H9, rounded corners I20 of the.

cam -like portion engage a machined pad IZI on the transverse member I1 and force thistransverse member downwardly until the handle H9 is .in a vertical position and the lower surface of the transverse member I I rests against nuts I 22 which are adjustably threaded on the post II5 thus locking the beam I5 to the base It.

In conditioning the device for operation, the properreceiver M for the type of propeller blade to be balanced is first attached to the crossmember 38 by means of thebolts l2. Thecrcss arm M is then positioned so that its stops All will be in position to engage the blade at a point somewhatfbeyond its center of gravity. The static balance of the beam about its turning axis is then established by moving a balance weight I23 along a threaded rod 524 extending horizontally from the transverse member I! parallel to the longitudinal axis of the beam I5. When this moment or balance is established the indicator 61 is in registration with the zero indicium E9 on the chart I9. During this step the lever 24 is positively positioned on thelongitudinal axis of the beam 15 by turning the handle 53 which causes the thrusts 50 and 5], in the manner hereinbeforedescribed, to engage the pivot 2! in the lever 24 and this lever is also locked to the beam .by means of the trig lock I05;

.ters with the indiciuin E9 on the chart iii.

weight I25, mounted upon. a screw I26, which extends transversely between the arms 23, is shifted until the indicator 83 assumes a position in registration with the indicium 84. It, of course, is understood that in establishing the static balance of the beam I5 and the lever 24 the noises 85 and 89must be in their zero positions.

When the balance of the system has been established the beam 15 and the lever 24 are again locked by the means previously described and the propeller blade 43 is held horizontally with its shank directly above the receiverM and then lowered carefully therein. The blade is then securely locked in this receiver. by turning the clamping member-45 against the butt of the propeller shank and the other end of theblade is then supported, to relieve any strain, on the stops it which are adjusted into engagement with surface of the blade. i

In the operation of establishing the longitudinal static moment of a blade, after such blade has been mounted in the receiver, the beam I5 is unlocked so that it may oscillate about its turning axis, care being taken that the lever 24 is positively positioned on the longitudinal axis of the beam by the thrusts 5E! and Si in the manner hereinbeiore described and that the lever M is locked securely to the beam by the trig. lock I59. Weights I21, which are cylindrical in shape, are then threaded upon a bar I28 which is callbrated to a definite weight and this bar i283 is then placed on a V bearing formed by two adjustable rests I29 in the end of the beam E5. The number of weights placed on this bar must be such so that they do not quite counterbalance the weight of the blade on the opposite side of the turning axis of th'e beam, as indicated by the indicator 61. The poise Ed is then turned on the micrometer screw 86 until this indicator 3i regis- The sum of the weights I21 and the weight of the bar I28 plus the amount indicated by the poise (iii in the longitudinal static moment of the blade which, if within the predetermined. tolerance. is thenrecorded together with the serial number of the blade.

\The transverse static moment of this blade is now determined by locking the beam 5 to the base by turning the handle tit and unlocking the lever 24 from the beam I5 by opening the trig lock by means of the handle H3. The handle 53 is then turned and the thrusts 5i! and 5| disengaged from the ends of the pivot 25 so that the lever 2 mayoscillate freely. The noise this now moved into a position by means of the hand knob l lil' after loosening the clamp it? until the indicator 83 within the housing M}, which is mounted upon the beam i5, registers withdthe indicium 84 on the chart 85. The amount of this static moment, if within the predetermined tele ance, is then entered against the serialnumber of the blade on the record.

It will now be apparent that when it becomes necessary to replace this blade. another blade maybe conditioned in this manner so that its moments correspond to those recorded, It is, of course, obvious that when either the longitudinal or transverse static moment is not .Withinthe predetermined tolerance that material may be removed from the b1ade .1or added. to bring it within the tolerance without removing the blade from the receiver after securely locking the beam I all) only, and it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the sub- J'oined claims.

Having described the invention, I claim:

1. In a device of the class described, in combination, a base, a beam, fulcrum pivots extending laterally in said beam, bearings mounted on said base for the reception of said pivots and forming a rocking axis for said beam, a plurality of bearings mounted on the longitudinal axis of said beam and in a horizontal plane passing through said'fulcrum pivots, a lever pivoted on said bearings and means comprising relatively movable members having a common actuator for definitely positioning saidlever on'th'e longitudinal axis oi said beam with respect to its rocking axis.

7 2. In a device of the class described, in combination, a base, a beam, pivots extending laterally in said beam, bearings mounted on said base for the reception of said pivots forming a rocking axis for said beam, a plurality of bearings mounted on said beam and positioned in its longitudinal axis, a lever pivoted on said bearings, means comprising relatively movable members for definitely positioning said lever on the longitudinal axis of said beam with respect to its rocking axis and means for independently preventing relative movement between said base and said beam and between said beam and said lever.

3. In a device of the class described, in combination, a base, a beam, aligned pivots in said beam for oscill-atably mounting said beam upon said base, a plurality of hearings on said beam, said bearings being mounted in alignment perpendicular to the pivotal axis of said beam, a lever pivotally mounted on said bearings, means for definitely positioning said lever with respect to said beam, a pendulated indicator operatively connected to said beam, another pendulated inclicator operatively connected to said lever for indicating their conditions of balance, one of said pendulated indicators being pivotally mounted on said beam and the other of said pendulated indicators being pivotally mounted on said base.

4. In a device of the class described, in combination, a base, a beam, fulcrum pivots extending laterally in said beam, bearings mounted on said base for the reception of said pivots and forming a rocking axis for said beam, a plurality of bearings mounted on the longitudinal axis of said beam and in a horizontal plane passing through said fulcrum pivots, a lever pivoted on said bearings, means comprising relatively movable members for definitely positioning said lever on the longitudinal axis of said beam with respect to its rocking axis and means for independently preventing relative movement between said base and said beam and between said beam and said lever. v

5. In a device of the class described, in combination, a base, a beam, fulcrum pivots extending laterally in said beam, bearings mounted on said base for the reception of said pivots and forming a rocking axis for said beam, a plurality of bearings mounted on the longitudinal axis of said beam and in a horizontal plane passing through said fulcrum pivots, a lever pivoted on said bearings, means comprising relatively movable members for definitely positioning s'aidlever on the longitudinal axis of said beam with respect to its rocking axis, means for independently preventing relative movement between said base and said beam and between said beam and said lever, said movement preventing means comprising an adjustable stop on said base, movable means on said beam for moving and holding a portion of said beam in engagement with said adjustable stop and a stop and a movable member on said beam for moving and holding a portion. of said lever in engagement with said stop.

6. In a device of the class described, in combination, a base, a beam, fulcrum pivots extending laterally in said beam, bearings mounted on said base for the reception of said pivots and forming a rocking axis for said beam, a plurality of bearings mounted on the longitudinal axis of said beam, a lever pivoted on said bearings, means comprising relatively movable members for definitely positioning said lever on the longitudinal axis of said beam with respect to its rocking axis, said means comprising portions of said beam in alignment with and positioned on. opposite sides of a portion of said lever, stops in said beam portions having equal but opposite motion and common means for simultaneously imparting such opposite and equal motion to said stops for engaging said portion of said lever and moving said lever into predetermined position;

7. In a device of the class described, in combination, a base, a beam, fulcrum pivots extending laterally in said beam, bearings mounted on said base for the reception of said pivots and forming a rocking axis for said beam, a plurality of bearings mounted on the longitudinal axis of said beam, a lever pivoted on said bearings, means comprising relatively movable members for definitely positioning said lever, on the longitudinal axis of said beam with respect to its rocking axis, said means comprising portions of said beam in alignment with and positioned on opposite sides of a portion of said lever, threaded members in said lever portion having equal but opposite motion and common means for simultaneously imparting such Opposite and equal motion to said members for engaging said portion of said lever and moving said lever into predetermined position, one of said members being provided with a right hand thread and the other of said members being provided with a left hand thread, and said common, motion imparting means comprising a plurality of slightly flexible arms and a handle, connecting said arms, for

ered vertically, means for locking said propeller in said receiver, means forpreventing relative movement between said beam and said lever whereby said beam, said lever and said propeller blade rock as a unit about the rocking axis of said beam and means for supporting the free end of said propeller blade.

9. In a device of the class described, in combination, a base, a beam, means for oscillatably mounting said beam upon said base, a lever, means upon said beam for oscillatably mounting said lever upon said beam with its oscillating axis perpendicular to the oscillating axis of said beam,

propeller blade shank when the longitudinal axis of said propeller blade is horizontal and the propeller blade is lowered vertically, means for looking said propeller blade shank in said receiver and means for preventing relative movement between a said beam and said lever whereby said beam, said lever and said propeller blade rock as a unit about the rocking axis of said beam, means for counterbalancing the weight of 1 said propeller blade and means including a pendulated indicator for indieating the condition of balance of said assembly.

10. In a device of the class described, in combination, a base, a beam, means for oscillatably mounting said beam upon base, a lever,

means upon said beam for oscillatably mounting said lever upon said beam with its oscillating axis blade is lowered vertically, means for locking said propeller blade in said receiver, means for supporting the free end of said propeller blade and means for preventingrelative movement between said beam and said lever whereby said beam, said lever and propeller blade rock as a unit about the rocking axis of said beam, means for preventing .lever for indicating the condition of balance of said lever and of said lever and propeller blade.

11. In a device of the class described, in combination, a base, fulcrum bearings mounted upon said base, a beam, fulcrum pivots in said beam for rockably mountin saidbeam upon said bearings, said beam comprising a pair of longitudinally extending arms and a pair of transversely extending arms, bearings mounted upon said transversely extending armsin alignment with the longitudinal axis of said beam, a lever pivoted upon said bearings entirely on one side of said fulcrum pivots of said beam and lying between the longitudinal arms thereof, said plurality of bearings for said lever comprising at least two bearings facing in one direction and one bearing facing in the opposite direction, said oppositely facing bearing being springmrged in the direction in which it is facing and releasable means on said beam to force said lever into a predetermined position with respect to the fulcrum pivots of said beam.

12. In a device of the class described, in combination, a base", fulcrum bearings mounted upon said base, a beam, fulcrum pivots in said beam for rockably mounting said beam upon said bearings, said beam comprising a pair of longitudinally extending arms and'a pair of transversely extending arms, bearings mounted upon said transversely extending arms in alignment with the longitudinal axis of said beam, a lever pivoted upon said bearings entirely one side of, said fulcrum pivots of said beam and lying between the longitudinal arms thereof, said plurality of bearings for said lever comprising at least two bearings facing in one direction and one bearing fac- 'ing in the opposite direction, said oppositely facing bearing being spring-urged in the direction in which it is facing, releasable means on said beam to force said lever into a predetermined position with respect to the fulcrum pivots of said beam, means operatively connected to said beam and other means operatively connected to said lever for indicating independently their conditions of balance.

HALVOR O. HEM.

n r 5.. f.) 

